Various solvents, such as benzene, alcohol and chloroform, will dissolve out the pigment, leaving the plastid colorless.
The working of it is not at all completely understood at present, nor can we say exactly what is the part played by the pigment and what is the rfile of the protoplasm of the plastid.
More emphasis is, however, now laid on the action of the plastid in polymerization, while the initial stages are still not definitely ezplaincd.
In some cases the plastid disappears and the crystalline pigment only is left.
Whether the formation of the starch grain is due to a secretion from the plastid (Meyer, 1895) or to a direct transformation of the proteid of the plastid (Timberlake, 1901) has not been definitely established.